49721aa1315fc44bf46d73d343ace4e7c3dc785e
[libav.git] / libavformat / avio.h
1 /*
2 * copyright (c) 2001 Fabrice Bellard
3 *
4 * This file is part of Libav.
5 *
6 * Libav is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * Libav is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with Libav; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20 #ifndef AVFORMAT_AVIO_H
21 #define AVFORMAT_AVIO_H
22
23 /**
24 * @file
25 * @ingroup lavf_io
26 * Buffered I/O operations
27 */
28
29 #include <stdint.h>
30
31 #include "libavutil/common.h"
32 #include "libavutil/dict.h"
33 #include "libavutil/log.h"
34
35 #include "libavformat/version.h"
36
37 /**
38 * Seeking works like for a local file.
39 */
40 #define AVIO_SEEKABLE_NORMAL (1 << 0)
41
42 /**
43 * Seeking by timestamp with avio_seek_time() is possible.
44 */
45 #define AVIO_SEEKABLE_TIME (1 << 1)
46
47 /**
48 * Callback for checking whether to abort blocking functions.
49 * AVERROR_EXIT is returned in this case by the interrupted
50 * function. During blocking operations, callback is called with
51 * opaque as parameter. If the callback returns 1, the
52 * blocking operation will be aborted.
53 *
54 * No members can be added to this struct without a major bump, if
55 * new elements have been added after this struct in AVFormatContext
56 * or AVIOContext.
57 */
58 typedef struct AVIOInterruptCB {
59 int (*callback)(void*);
60 void *opaque;
61 } AVIOInterruptCB;
62
63 /**
64 * Different data types that can be returned via the AVIO
65 * write_data_type callback.
66 */
67 enum AVIODataMarkerType {
68 /**
69 * Header data; this needs to be present for the stream to be decodeable.
70 */
71 AVIO_DATA_MARKER_HEADER,
72 /**
73 * A point in the output bytestream where a decoder can start decoding
74 * (i.e. a keyframe). A demuxer/decoder given the data flagged with
75 * AVIO_DATA_MARKER_HEADER, followed by any AVIO_DATA_MARKER_SYNC_POINT,
76 * should give decodeable results.
77 */
78 AVIO_DATA_MARKER_SYNC_POINT,
79 /**
80 * A point in the output bytestream where a demuxer can start parsing
81 * (for non self synchronizing bytestream formats). That is, any
82 * non-keyframe packet start point.
83 */
84 AVIO_DATA_MARKER_BOUNDARY_POINT,
85 /**
86 * This is any, unlabelled data. It can either be a muxer not marking
87 * any positions at all, it can be an actual boundary/sync point
88 * that the muxer chooses not to mark, or a later part of a packet/fragment
89 * that is cut into multiple write callbacks due to limited IO buffer size.
90 */
91 AVIO_DATA_MARKER_UNKNOWN,
92 /**
93 * Trailer data, which doesn't contain actual content, but only for
94 * finalizing the output file.
95 */
96 AVIO_DATA_MARKER_TRAILER
97 };
98
99 /**
100 * Bytestream IO Context.
101 * New fields can be added to the end with minor version bumps.
102 * Removal, reordering and changes to existing fields require a major
103 * version bump.
104 * sizeof(AVIOContext) must not be used outside libav*.
105 *
106 * @note None of the function pointers in AVIOContext should be called
107 * directly, they should only be set by the client application
108 * when implementing custom I/O. Normally these are set to the
109 * function pointers specified in avio_alloc_context()
110 */
111 typedef struct AVIOContext {
112 /**
113 * A class for private options.
114 *
115 * If this AVIOContext is created by avio_open2(), av_class is set and
116 * passes the options down to protocols.
117 *
118 * If this AVIOContext is manually allocated, then av_class may be set by
119 * the caller.
120 *
121 * warning -- this field can be NULL, be sure to not pass this AVIOContext
122 * to any av_opt_* functions in that case.
123 */
124 const AVClass *av_class;
125 unsigned char *buffer; /**< Start of the buffer. */
126 int buffer_size; /**< Maximum buffer size */
127 unsigned char *buf_ptr; /**< Current position in the buffer */
128 unsigned char *buf_end; /**< End of the data, may be less than
129 buffer+buffer_size if the read function returned
130 less data than requested, e.g. for streams where
131 no more data has been received yet. */
132 void *opaque; /**< A private pointer, passed to the read/write/seek/...
133 functions. */
134 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size);
135 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size);
136 int64_t (*seek)(void *opaque, int64_t offset, int whence);
137 int64_t pos; /**< position in the file of the current buffer */
138 int must_flush; /**< true if the next seek should flush */
139 int eof_reached; /**< true if eof reached */
140 int write_flag; /**< true if open for writing */
141 int max_packet_size;
142 unsigned long checksum;
143 unsigned char *checksum_ptr;
144 unsigned long (*update_checksum)(unsigned long checksum, const uint8_t *buf, unsigned int size);
145 int error; /**< contains the error code or 0 if no error happened */
146 /**
147 * Pause or resume playback for network streaming protocols - e.g. MMS.
148 */
149 int (*read_pause)(void *opaque, int pause);
150 /**
151 * Seek to a given timestamp in stream with the specified stream_index.
152 * Needed for some network streaming protocols which don't support seeking
153 * to byte position.
154 */
155 int64_t (*read_seek)(void *opaque, int stream_index,
156 int64_t timestamp, int flags);
157 /**
158 * A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
159 */
160 int seekable;
161
162 /**
163 * A callback that is used instead of write_packet.
164 */
165 int (*write_data_type)(void *opaque, uint8_t *buf, int buf_size,
166 enum AVIODataMarkerType type, int64_t time);
167 /**
168 * If set, don't call write_data_type separately for AVIO_DATA_MARKER_BOUNDARY_POINT,
169 * but ignore them and treat them as AVIO_DATA_MARKER_UNKNOWN (to avoid needlessly
170 * small chunks of data returned from the callback).
171 */
172 int ignore_boundary_point;
173
174 /**
175 * Internal, not meant to be used from outside of AVIOContext.
176 */
177 enum AVIODataMarkerType current_type;
178 int64_t last_time;
179 } AVIOContext;
180
181 /**
182 * Return AVIO_FLAG_* access flags corresponding to the access permissions
183 * of the resource in url, or a negative value corresponding to an
184 * AVERROR code in case of failure. The returned access flags are
185 * masked by the value in flags.
186 *
187 * @note This function is intrinsically unsafe, in the sense that the
188 * checked resource may change its existence or permission status from
189 * one call to another. Thus you should not trust the returned value,
190 * unless you are sure that no other processes are accessing the
191 * checked resource.
192 */
193 int avio_check(const char *url, int flags);
194
195 /**
196 * Allocate and initialize an AVIOContext for buffered I/O. It must be later
197 * freed with av_free().
198 *
199 * @param buffer Memory block for input/output operations via AVIOContext.
200 * The buffer must be allocated with av_malloc() and friends.
201 * @param buffer_size The buffer size is very important for performance.
202 * For protocols with fixed blocksize it should be set to this blocksize.
203 * For others a typical size is a cache page, e.g. 4kb.
204 * @param write_flag Set to 1 if the buffer should be writable, 0 otherwise.
205 * @param opaque An opaque pointer to user-specific data.
206 * @param read_packet A function for refilling the buffer, may be NULL.
207 * @param write_packet A function for writing the buffer contents, may be NULL.
208 * @param seek A function for seeking to specified byte position, may be NULL.
209 *
210 * @return Allocated AVIOContext or NULL on failure.
211 */
212 AVIOContext *avio_alloc_context(
213 unsigned char *buffer,
214 int buffer_size,
215 int write_flag,
216 void *opaque,
217 int (*read_packet)(void *opaque, uint8_t *buf, int buf_size),
218 int (*write_packet)(void *opaque, uint8_t *buf, int buf_size),
219 int64_t (*seek)(void *opaque, int64_t offset, int whence));
220
221 void avio_w8(AVIOContext *s, int b);
222 void avio_write(AVIOContext *s, const unsigned char *buf, int size);
223 void avio_wl64(AVIOContext *s, uint64_t val);
224 void avio_wb64(AVIOContext *s, uint64_t val);
225 void avio_wl32(AVIOContext *s, unsigned int val);
226 void avio_wb32(AVIOContext *s, unsigned int val);
227 void avio_wl24(AVIOContext *s, unsigned int val);
228 void avio_wb24(AVIOContext *s, unsigned int val);
229 void avio_wl16(AVIOContext *s, unsigned int val);
230 void avio_wb16(AVIOContext *s, unsigned int val);
231
232 /**
233 * Write a NULL-terminated string.
234 * @return number of bytes written.
235 */
236 int avio_put_str(AVIOContext *s, const char *str);
237
238 /**
239 * Convert an UTF-8 string to UTF-16LE and write it.
240 * @param s the AVIOContext
241 * @param str NULL-terminated UTF-8 string
242 *
243 * @return number of bytes written.
244 */
245 int avio_put_str16le(AVIOContext *s, const char *str);
246
247 /**
248 * Convert an UTF-8 string to UTF-16BE and write it.
249 * @param s the AVIOContext
250 * @param str NULL-terminated UTF-8 string
251 *
252 * @return number of bytes written.
253 */
254 int avio_put_str16be(AVIOContext *s, const char *str);
255
256 /**
257 * Mark the written bytestream as a specific type.
258 *
259 * Zero-length ranges are omitted from the output.
260 *
261 * @param time the stream time the current bytestream pos corresponds to
262 * (in AV_TIME_BASE units), or AV_NOPTS_VALUE if unknown or not
263 * applicable
264 * @param type the kind of data written starting at the current pos
265 */
266 void avio_write_marker(AVIOContext *s, int64_t time, enum AVIODataMarkerType type);
267
268 /**
269 * ORing this as the "whence" parameter to a seek function causes it to
270 * return the filesize without seeking anywhere. Supporting this is optional.
271 * If it is not supported then the seek function will return <0.
272 */
273 #define AVSEEK_SIZE 0x10000
274
275 /**
276 * Passing this flag as the "whence" parameter to a seek function causes it to
277 * seek by any means (like reopening and linear reading) or other normally unreasonable
278 * means that can be extremely slow.
279 * This may be ignored by the seek code.
280 */
281 #define AVSEEK_FORCE 0x20000
282
283 /**
284 * fseek() equivalent for AVIOContext.
285 * @return new position or AVERROR.
286 */
287 int64_t avio_seek(AVIOContext *s, int64_t offset, int whence);
288
289 /**
290 * Skip given number of bytes forward
291 * @return new position or AVERROR.
292 */
293 static av_always_inline int64_t avio_skip(AVIOContext *s, int64_t offset)
294 {
295 return avio_seek(s, offset, SEEK_CUR);
296 }
297
298 /**
299 * ftell() equivalent for AVIOContext.
300 * @return position or AVERROR.
301 */
302 static av_always_inline int64_t avio_tell(AVIOContext *s)
303 {
304 return avio_seek(s, 0, SEEK_CUR);
305 }
306
307 /**
308 * Get the filesize.
309 * @return filesize or AVERROR
310 */
311 int64_t avio_size(AVIOContext *s);
312
313 /** @warning currently size is limited */
314 int avio_printf(AVIOContext *s, const char *fmt, ...) av_printf_format(2, 3);
315
316 void avio_flush(AVIOContext *s);
317
318
319 /**
320 * Read size bytes from AVIOContext into buf.
321 * @return number of bytes read or AVERROR
322 */
323 int avio_read(AVIOContext *s, unsigned char *buf, int size);
324
325 /**
326 * @name Functions for reading from AVIOContext
327 * @{
328 *
329 * @note return 0 if EOF, so you cannot use it if EOF handling is
330 * necessary
331 */
332 int avio_r8 (AVIOContext *s);
333 unsigned int avio_rl16(AVIOContext *s);
334 unsigned int avio_rl24(AVIOContext *s);
335 unsigned int avio_rl32(AVIOContext *s);
336 uint64_t avio_rl64(AVIOContext *s);
337 unsigned int avio_rb16(AVIOContext *s);
338 unsigned int avio_rb24(AVIOContext *s);
339 unsigned int avio_rb32(AVIOContext *s);
340 uint64_t avio_rb64(AVIOContext *s);
341 /**
342 * @}
343 */
344
345 /**
346 * Read a string from pb into buf. The reading will terminate when either
347 * a NULL character was encountered, maxlen bytes have been read, or nothing
348 * more can be read from pb. The result is guaranteed to be NULL-terminated, it
349 * will be truncated if buf is too small.
350 * Note that the string is not interpreted or validated in any way, it
351 * might get truncated in the middle of a sequence for multi-byte encodings.
352 *
353 * @return number of bytes read (is always <= maxlen).
354 * If reading ends on EOF or error, the return value will be one more than
355 * bytes actually read.
356 */
357 int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen);
358
359 /**
360 * Read a UTF-16 string from pb and convert it to UTF-8.
361 * The reading will terminate when either a null or invalid character was
362 * encountered or maxlen bytes have been read.
363 * @return number of bytes read (is always <= maxlen)
364 */
365 int avio_get_str16le(AVIOContext *pb, int maxlen, char *buf, int buflen);
366 int avio_get_str16be(AVIOContext *pb, int maxlen, char *buf, int buflen);
367
368
369 /**
370 * @name URL open modes
371 * The flags argument to avio_open must be one of the following
372 * constants, optionally ORed with other flags.
373 * @{
374 */
375 #define AVIO_FLAG_READ 1 /**< read-only */
376 #define AVIO_FLAG_WRITE 2 /**< write-only */
377 #define AVIO_FLAG_READ_WRITE (AVIO_FLAG_READ|AVIO_FLAG_WRITE) /**< read-write pseudo flag */
378 /**
379 * @}
380 */
381
382 /**
383 * Use non-blocking mode.
384 * If this flag is set, operations on the context will return
385 * AVERROR(EAGAIN) if they can not be performed immediately.
386 * If this flag is not set, operations on the context will never return
387 * AVERROR(EAGAIN).
388 * Note that this flag does not affect the opening/connecting of the
389 * context. Connecting a protocol will always block if necessary (e.g. on
390 * network protocols) but never hang (e.g. on busy devices).
391 * Warning: non-blocking protocols is work-in-progress; this flag may be
392 * silently ignored.
393 */
394 #define AVIO_FLAG_NONBLOCK 8
395
396 /**
397 * Create and initialize a AVIOContext for accessing the
398 * resource indicated by url.
399 * @note When the resource indicated by url has been opened in
400 * read+write mode, the AVIOContext can be used only for writing.
401 *
402 * @param s Used to return the pointer to the created AVIOContext.
403 * In case of failure the pointed to value is set to NULL.
404 * @param url resource to access
405 * @param flags flags which control how the resource indicated by url
406 * is to be opened
407 * @return 0 in case of success, a negative value corresponding to an
408 * AVERROR code in case of failure
409 */
410 int avio_open(AVIOContext **s, const char *url, int flags);
411
412 /**
413 * Create and initialize a AVIOContext for accessing the
414 * resource indicated by url.
415 * @note When the resource indicated by url has been opened in
416 * read+write mode, the AVIOContext can be used only for writing.
417 *
418 * @param s Used to return the pointer to the created AVIOContext.
419 * In case of failure the pointed to value is set to NULL.
420 * @param url resource to access
421 * @param flags flags which control how the resource indicated by url
422 * is to be opened
423 * @param int_cb an interrupt callback to be used at the protocols level
424 * @param options A dictionary filled with protocol-private options. On return
425 * this parameter will be destroyed and replaced with a dict containing options
426 * that were not found. May be NULL.
427 * @return 0 in case of success, a negative value corresponding to an
428 * AVERROR code in case of failure
429 */
430 int avio_open2(AVIOContext **s, const char *url, int flags,
431 const AVIOInterruptCB *int_cb, AVDictionary **options);
432
433 /**
434 * Close the resource accessed by the AVIOContext s and free it.
435 * This function can only be used if s was opened by avio_open().
436 *
437 * The internal buffer is automatically flushed before closing the
438 * resource.
439 *
440 * @return 0 on success, an AVERROR < 0 on error.
441 * @see avio_closep
442 */
443 int avio_close(AVIOContext *s);
444
445 /**
446 * Close the resource accessed by the AVIOContext *s, free it
447 * and set the pointer pointing to it to NULL.
448 * This function can only be used if s was opened by avio_open().
449 *
450 * The internal buffer is automatically flushed before closing the
451 * resource.
452 *
453 * @return 0 on success, an AVERROR < 0 on error.
454 * @see avio_close
455 */
456 int avio_closep(AVIOContext **s);
457
458
459 /**
460 * Open a write only memory stream.
461 *
462 * @param s new IO context
463 * @return zero if no error.
464 */
465 int avio_open_dyn_buf(AVIOContext **s);
466
467 /**
468 * Return the written size and a pointer to the buffer. The buffer
469 * must be freed with av_free().
470 * Padding of AV_INPUT_BUFFER_PADDING_SIZE is added to the buffer.
471 *
472 * @param s IO context
473 * @param pbuffer pointer to a byte buffer
474 * @return the length of the byte buffer
475 */
476 int avio_close_dyn_buf(AVIOContext *s, uint8_t **pbuffer);
477
478 /**
479 * Iterate through names of available protocols.
480 *
481 * @param opaque A private pointer representing current protocol.
482 * It must be a pointer to NULL on first iteration and will
483 * be updated by successive calls to avio_enum_protocols.
484 * @param output If set to 1, iterate over output protocols,
485 * otherwise over input protocols.
486 *
487 * @return A static string containing the name of current protocol or NULL
488 */
489 const char *avio_enum_protocols(void **opaque, int output);
490
491 /**
492 * Pause and resume playing - only meaningful if using a network streaming
493 * protocol (e.g. MMS).
494 *
495 * @param h IO context from which to call the read_pause function pointer
496 * @param pause 1 for pause, 0 for resume
497 */
498 int avio_pause(AVIOContext *h, int pause);
499
500 /**
501 * Seek to a given timestamp relative to some component stream.
502 * Only meaningful if using a network streaming protocol (e.g. MMS.).
503 *
504 * @param h IO context from which to call the seek function pointers
505 * @param stream_index The stream index that the timestamp is relative to.
506 * If stream_index is (-1) the timestamp should be in AV_TIME_BASE
507 * units from the beginning of the presentation.
508 * If a stream_index >= 0 is used and the protocol does not support
509 * seeking based on component streams, the call will fail with ENOTSUP.
510 * @param timestamp timestamp in AVStream.time_base units
511 * or if there is no stream specified then in AV_TIME_BASE units.
512 * @param flags Optional combination of AVSEEK_FLAG_BACKWARD, AVSEEK_FLAG_BYTE
513 * and AVSEEK_FLAG_ANY. The protocol may silently ignore
514 * AVSEEK_FLAG_BACKWARD and AVSEEK_FLAG_ANY, but AVSEEK_FLAG_BYTE will
515 * fail with ENOTSUP if used and not supported.
516 * @return >= 0 on success
517 * @see AVInputFormat::read_seek
518 */
519 int64_t avio_seek_time(AVIOContext *h, int stream_index,
520 int64_t timestamp, int flags);
521
522 #endif /* AVFORMAT_AVIO_H */